Described below is a method for encoding a sequence of digitized images formed by a plurality of pixels having associated pixel values, as well as to a corresponding decoding method and a corresponding encoder and decoder.
In a plurality of technical application fields it is desirable to compress digitized images as well as possible with low losses in order to keep the storage space required for the images small. In addition it is often necessary to retrieve large volumes of data from digitized images as quickly as possible from a memory over a transmission network, even with a restricted bandwidth, in which case minor losses during the compression of the image data can also be accepted if necessary.
Digitized image sequences occur in areas such as medical applications, in which for example with X-ray imaging by a computed tomograph a sequence of two-dimensional slice images of organs of the patient being X-rayed are generated, with the slice images being acquired at a certain spatial distance from each other. Various compression methods for lossless compression of such image data are known from the related art, with this method also being employed for any other digitized images. In particular the standards JPEG-LS or JPEG-2000 are used for compression in which the individual images of the image sequence are compressed independently of each other. In such methods an existing correlation between the individual consecutive images is not exploited.
Various video encoding standards are also known in the related art which are used for compression of moving image content, especially of video films. In the H.264/AVC encoding standard, image blocks of consecutive images are predicted with the aid of movement compensation. The prediction error produced is then encoded.